Here is how to get into contact with Canada Post, and some other important numbers.
Numbers From Their Website:

General Information

By email    |     Phone: 1 800 267-1177

This number allowed me to talk to someone directly. Also, this allows you to talk directly with the person in charge of your claim without having to call long distance (another tactic to try and defer you from calling them so much). All you do is call this number and go through the system until you talk to someone. Once on, ask them to put you through to your claims agent, and give them the telephone number (My agent was H. Laplant (very rude), and her number is 1-514-345-4503, so just tell them your agent name/number). This will keep you from getting long distance charges for something that is not your fault in the first place.

Accounts Management (Billing inquiries/credit and collection)

By email    |     Phone: 1 800 267-7651    |    Fax: 1 613 734-9092

Distribution Services & Delivery Inquiries (Priority Courier, Xpresspost, Parcels & International Couriers)

By email    |     Phone: 1 888 550-6333

From outside of Canada

By email    |     Phone: 1 416 979-8822

TDD

By email    |     Phone: 1 800 267-2797